Filter cartridge assembly

ABSTRACT

A filter cartridge assembly ( 10 ) comprising respective disposable elements ( 11 ) positioned either side of a three part reusable flow through spacer means ( 12 ), the spacer means ( 12 ) comprises three parts, opposed support sections ( 19  and  20 ) and an outer locator ring ( 21 ). The support sections ( 19  and  20 ) have filtrate flow through passages ( 22 ) and abutment flanges ( 23 ) which abut to provide radial flow through passages ( 24 ). Each of the supports (19 and 20) include circular ridges ( 25  and  26 ) at the inner and outer peripheral edges designed to push into the paper roll ( 16 ) while O-rings ( 27  and  28 ) provide seals between the supports ( 19  and  20 ) and the ring ( 21 ) and the outer body ( 13 ) of the respective elements ( 11 ).

TECHNICAL FIELD OF THE INVENTION

[0001] THIS INVENTION relates to a filter cartridge assembly and inparticular, but not limited to, a filter cartridge suitable forfiltering oil or fuel.

BACKGROUND TO THE INVENTION

[0002] Filters are known that employ an outer filter body holdingdisposable filter cartridges, the outer body usually has a cylindricalhousing and a cap, a coaxial return pipe usually has a threaded end andthe cap screws onto the threaded end to clamp the cartridges inoperative position in the housing. Liquid flows though an inlet, throughfilter media in the cartridges and out through the return pipe. Spentcartridges are simply exchanged with new ones. Typical cartridges areknown that are made from a paper roll held in a plastics or metalcylinder. An example is described in WO/0037232. There are variousalternative constructions and flow modalities used.

[0003] European patent application No. P 0 556 506A1 describes a modularfilter system consisting of cartridges made from a tightly wrapped paperfilter media retained in a plastic casing. The plastic casing hasintegrally formed grate-like configuration on its top and bottomsurfaces to allow fluid to enter an exit the filter. The casing is alsodimensioned to closely surround the paper media. The filter cartridgesare stackable within the filter housing which can retain a plurality ofcartridges thereby increasing the capacity of the filter. Each casing ismade from identical top and bottom halves where the cylindrical wallsclip together around the paper roll. When two cartridges are used thegrid like top of one cartridge a butts the grid-like bottom of the otherso that liquid flows from one cartridge to the next in series. Thusliquid flows one way, from one end only and is recovered out the otherend. The central pipe in this case is an inlet pipe rather than a returnpipe.

[0004] Other arrangements are known where liquid flows simultaneouslyinto the filter in opposite directions and is recovered centrally, seefor example Australian Patent 729523 and U.S. Pat. No. 4,792,397.

[0005] Australian Patent 729523 and WO/0037232 describe an injectionmoulded filter cartridge filled with a paper roll filter media. Unlikethe cartridge of European patent application No. P 0 556 506A1, thecartridge is open ended and does not employ grate-like ends. This allowsa press to be used to insert paper rolls under pressure. In onecartridge opposite ends of the cartridge are completely open so thecartridge is effectively a tube with two back-to-back paper rollsseparated by gauze providing a return flow path. The paper rolls have acentral bore made of cardboard for a return pipe. Thus when thecartridge is clamped inside a filter container liquid flows from aninlet in the container in both ends of the cartridge, through the paperrolls and is recovered by flowing out the ends of the paper rollsthrough a common return path formed by the gauze to the central returnpipe. The gauze separates the confronting ends of the rolls and providesa flow path for the filtered liquid. Gauze is also used in thearrangement of Australian patent 659793 to separate two paper rolls in ametal cannister.

[0006] In U.S. Pat. No. 4,792,397 back-to-back paper rolls are used in asimilar arrangement Australian Patent 729523 and WO/0037232 exceptinstead of gauze being used to separate the rolls U.S. Pat. No.4,792,397 uses a specially made fluid collector between the rolls. Thefluid collector has closely spaced concentric ridges projecting fromopposite sides of a substantially flat portion, pressure equalisationholes pass through the flat portion. The ridges push into the paperrolls on opposite sides of the collectors. Gaps in each ridge allowsradial return flow to the central return pipe.

[0007] In Australian patent 650176 a metal canister is provided with endwall depressions to improve radial return flow. In Australian patentapplication 59243/00 a fluid collector is provided in an end wall of thehousing, the fluid collector has lands in the form of sectors of acircle separated by radial flow passages.

[0008] The prevailing design criteria adopted in all these instances isto support the paper across its ends in an effort to maintain the returnflow and minimise blockages that might impede flow as the papercollapses. Since the filters are pressurised as the filter media agesand becomes loaded it may distort in the region of the return flowleading to blockages. The gauze may become depressed by the paper beingforced across the gap. Thus in the above examples it is usual to providea substantial amount of support at the end of the paper roll with fluidcollectors with relatively large flow paths being preferred to wiregauze.

[0009] The present invention adopts a completely different approach tothe problem of supporting the roll while maintaining greater efficiencyof return flow across the filter.

OUTLINE OF THE INVENTION

[0010] In one aspect the present invention resides in a filter cartridgeassembly assembled form two disposable filter elements and spacer meansholding the filter elements in separate spaced apart relationship, eachfilter element comprising an outer housing containing an annular papercore, characterised in that the spacer means comprises a reusableback-to-back filter element support means with through holes for flow offiltrate flowing through the annular paper core into the spacer means,the spacer means having cross flow passage means within said spacermeans for inward flow of said filtrate for return through a return pipe,the spacer means being supported by a reusable outer locator ring inwhich the spacer means is located and which extends in oppositedirections outside a peripheral marginal portion of the housings of therespective disposable filter elements.

[0011] Typically, the outer ring includes O-ring holders to hold sealingrings which seal the locator ring against the spacer and the peripheralmarginal portions of the of the housings of filter elements.

[0012] Preferably, the spacers include upstanding outer ridges thatpenetrate peripheral portions of the paper core and there being onopposite sides of the spacer means a plurality of ridges that hold thepaper roll and support it, defining transverse flow channels leading tosaid through holes promoting flow along the spacer in the channels tothe spaced through holes.

[0013] Preferably, the spacer is made from two disc members havingcircumferentially spaced mating abutments, gaps between the abutmentsdefining return flow through passage means.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order that the present invention can be more readilyunderstood and be put into practical effect, reference will now be madeto the accompanying drawings which illustrate a preferred embodiment ofthe invention and wherein:

[0015]FIG. 1 is a section through a filter cartridge assembly accordingto the invention;

[0016]FIGS. 2 and 3 are respective plan and section views of a spacerand locator ring as assembled; whilst

[0017]FIG. 4 is a detailed view of a typical outer circular ridge.

METHOD OF PERFORMANCE

[0018] Referring to the drawings and initially to FIG. 1 there isillustrated a filter cartridge assembly 10 comprising respectivedisposable filter elements 11 positioned either side of a three partreusable flow through spacer means 12, each of the filter elements 11comprises a hollow cylindrical plastics outer body 13 which has internalribs 14 spaced along its inner surface 15 to provide an anti trackingfunction inhibiting flow along the interface between annular paperfilters 16 and the outer body 13.

[0019] Annular paper roll filters 16 have been pushed, undercompression, into the plastics outer bodies 13 of the respectiveelements 11. Each of the paper filters 16 has a central cylindricalcardboard core 17. Thus a complete passage is formed through theassembly at 18 so that a filtrate return pipe can be inserted throughand also used to provide in conjunction with a filter housing(not shown)a clamp against opposite ends of the assembly to clamp the assemblytogether.

[0020] The spacer means 12 comprises three cast metal parts, opposedsupport sections 19 and 20 and an outer locator ring 21. The supportsections 19 and 20 have filtrate flow through passages 22 and abutmentflanges 23 which abut as shown providing radial flow through passages24. This means that filtrate can flow through the paper filter 16,through the flow through holes at 22 and their associated surface flowchannels and then radially through the apertures 24 to a return(notshown). Each of the supports 19 and 20 include circular ridges 25 and 26at the inner and outer peripheral edges designed to push into the paperroll 16 while O-rings 27 and 28 provide seals between the supports 19and 20 and the ring 21 and the outer body 13 of the respective elements11.

[0021] Whilst the above has been given by way of illustrative example ofthe present invention many variations and modifications thereto will beapparent to those skilled in the art without departing from the broadambit and scope of the invention as set out in the appended claims.

1. A filter cartridge assembly assembled from two disposable filterelements and spacer means holding the filter elements in separate spacedapart relationship, each filter element comprising an outer housingcontaining an annular paper core, characterised in that the spacer meanscomprises a reusable back-to-back filter element support means withthrough holes for flow of filtrate flowing through the annular papercore into the spacer means, the spacer means having cross flow passagemeans within said spacer means for inward flow of said filtrate forreturn through a return pipe, the spacer means being supported by areusable outer locator ring in which the spacer means is located andwhich extends in opposite directions outside a peripheral marginalportion of the housings of the respective disposable filter elements. 2.A filter cartridge assembly according to claim 1 wherein the outer ringincludes O-ring holders to hold sealing rings which seal the locatorring against the spacer means and the peripheral marginal portions ofthe of the housings of filter elements.
 3. A filter cartridge assemblyaccording to claim 1 wherein the spacer means includes upstanding outerridges that penetrate peripheral portions of the paper core and therebeing on opposite sides of the spacer means a plurality of ridges thathold the paper roll and support it, defining transverse flow channelsleading to said through holes promoting flow along the spacer in thechannels to the spaced through holes.
 4. A filter cartridge assemblyaccording to claim 1 wherein the spacer means is made from two discmembers having circumferentially spaced mating abutments, gaps betweenthe abutments defining return flow through passage means.
 5. A filtercartridge assembly according to claim 1 wherein the outer ring includesO-ring holders to hold sealing rings which seal the locator ring againstthe spacer and the peripheral marginal portions of the of the housingsof filter elements, the spacer including upstanding outer ridges thatpenetrate peripheral portions of the paper core and there being onopposite sides of the spacer means a plurality of ridges that hold thepaper roll and support it, the ridges defining transverse flow channelsleading to said through holes promoting flow along the spacer in thechannels to the spaced through holes.
 6. A filter cartridge assemblyaccording to claim 1 wherein the outer ring includes O-ring holders tohold sealing rings which seal the locator ring against the spacer meansand the peripheral marginal portions of the of the housings of filterelements, the spacer means being two disc members havingcircumferentially spaced mating abutments, gaps between the abutmentsdefining return flow through passage means.
 7. A filter cartridgeassembly according to claim 1 wherein the spacer means includesupstanding outer ridges that penetrate peripheral portions of the papercore and there being on opposite sides of the spacer means a pluralityof ridges that hold the paper roll and support it, the ridges definingtransverse flow channels leading to said through holes promoting flowalong the spacer in the channels to the spaced through, the spacer meanscomprising two disc members having circumferentially spaced matingabutments, gaps between the abutments defining return flow throughpassage means.